Speckled Alder

Speckled Alder
Swamp Alder 
 
Alnus incana ssp. rugosa
 
Speckled Alder is a fast-growing, nitrogen-fixing native shrub or small tree that plays a critical ecological role in wetlands, riparian zones, and disturbed landscapes across Ontario and eastern North America. Exceptionally hardy and adaptable, it is a keystone species for restoration projects, streambank stabilization, and wildlife habitat creation.
This species thrives where others struggle—poor soils, fluctuating water levels, and exposed sites—while actively improving soil health for surrounding plant communities.
 
Growth Habit
Multi-stemmed shrub or small tree
Height: 3–7 m
Width: 3–5 m
Upright, spreading form with strong root systems
 
Growing Conditions
Light: Full sun to partial shade
Moisture: Moist to wet soils; tolerates seasonal flooding
Soil: Clay, loam, sand; thrives in nutrient-poor soils
pH: Acidic to neutral
Hardiness: Zone 2–6
 
Ecological Value
Speckled Alder is a powerhouse for ecosystem recovery and biodiversity:
Nitrogen fixation: Forms symbiotic relationships with Frankia bacteria, enriching soils naturally
Erosion control: Extensive root systems stabilize streambanks and shorelines
Successional support: Prepares degraded sites for long-term forest regeneration
Wildlife habitat: Dense growth provides cover and nesting opportunities
Seeds and buds are consumed by birds such as finches and grouse, while browse supports deer and beaver.
 
Larval Host Plant Value 
Speckled Alder is an important larval host plant for several native moths and butterflies, making it essential for sustaining insect biodiversity and food webs.
It supports larvae of:
The Columbine Moth (Schinia rectifascia)
The Alder Kitten Moth (Furcula scolopendrina)
Several Geometrid and Noctuid moth species
Alder-feeding caterpillars are a vital food source for:
Songbirds during nesting season
Amphibians and small mammals
Predatory insects
By planting Speckled Alder, you are directly supporting multi-trophic ecological relationships, from microbes and insects to birds and mammals—an essential step in restoring functional ecosystems.
 
Landscape & Restoration Uses
Wetland restoration
Riparian buffers
Shoreline stabilization
Reforestation and successional planting
Naturalized hedgerows
 
Why Plant Speckled Alder?
Because ecosystems don’t rebuild themselves without help—and this plant does a lot of the heavy lifting.
 
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